1. Field of the Invention
The present invention relates to a method, system, and program for configuring shared devices over a fabric.
2. Description of the Related Art
In certain computing environments, multiple host systems may communicate with a control unit, such as an IBM Enterprise Storage Server (ESS)®, for data in a storage device managed by the ESS receiving the request. The control unit provides access to storage devices, such as interconnected hard disk drives through one or more logical paths. (IBM and ESS are registered trademarks of IBM). The interconnected drives may be configured as a Direct Access Storage Device (DASD), Redundant Array of Independent Disks (RAID), Just a Bunch of Disks (JBOD), etc. The control unit may include duplicate and redundant processing complexes, also known as clusters, to allow for failover to a surviving cluster in case one fails. The clusters may access shared devices.
During initialization, each processing complex in the control unit is responsible for configuring parts of the fabric, such as a Fibre Channel Arbitrated loop, providing a connection to the shared adaptors. For instance, one processing complex configures a first part of the fabric connected to a first set of shared adaptors and another processing complex configures a second part of the fabric connected to a second set of shared adaptors. Device drivers in the processing complex then configure the shared adaptors. However, if one processing complex is down during initialization, then that part of the fabric that is configured by the failed processing complex will remain uninitialized and the surviving processing complex will not have access to the shared adaptors accessed through that part of the fabric that is supposed to be configured by the failed processing complex. The surviving processing complex will however have access and use those shared adaptors accessible through the portion of the fabric configured by the surviving processing complex.